I replaced one OEM steering knuckle ball joint at ~180K miles due to minimal play and a torn boot. The car now has ~210K on it and the reasonably expensive replacement ball joint (with a zerk) now clicks audibly under some conditions. I probably would have been better off leaving the OEM joint in place, and I don't really feel like replacing it again. For me, it's OEM whenever possible. In this particular case, OEM comes with a complete steering knuckle, so $50 vs. $500. If I have to do the other side, it will be OEM.